I am quite sure the first one is Friction, but I am not sure about the second one. Is it wind?
let the distance of pillar is "r" from one end of the slab
So here net torque must be balance with respect to pillar to be in balanced state
So here we will have

here we know that
mg = 19600 N
Mg = 400,000 N
L = 20 m
from above equation we have



so pillar is at distance 10.098 m from one end of the slab
F=W=mg
12N(given)= m*9.8
m= 1.22 kg
Answer:
Sound intensity is measured with a sound level meter or Sound pressure Level (SPL) Meter.
Explanation:-
It measure sound intensity is the sound pressure level. The unit of measurement is decibels.
The answer is B for sure !